The longer the employee has worked in one hotel, the more rights s/he has in choosing the shift, the lenght of paid holidays etc. Changing workplace means starting all over again. There are lenght of employment, as well as department seniorities.
A part time employee, who is called in when extra help is needed at the hotel. Might have two or three constant shifts a week. Most steady extras hope to raise to a full-time position. The pay is lower and it is difficult to have a second job, as one has to be on constant call.